1. Field of the Invention
This invention relates to an apparatus for modifying the reproduction frequency band of a video signal.
2. Description of the Related Art
In a single-chip color CCD, color filters having characteristics that transmit an R, G or B color component are formed on photodiodes. The color filters are arrayed differently for each of the colors R, B and G. As a consequence, the reproduction frequency band of the R, G or B color signal output from the single-chip color CCD differs from one color signal to another. For example, the reproduction frequency band of the G color signal is broader than the reproduction frequency band of the R and B color signals.
In order to raise image resolution, it will suffice to widen the reproduction frequency band. However, the reproduction frequency band is decided on a per-color-signal basis. If the reproduction frequency band is always widened beyond the decided reproduction frequency band, false signals are produced and image quality declines. Though band limiting processing may be executed on a per-color-signal basis in order to eliminate false signals, such processing cannot be executed with an optical LPF (low-pass filter).
Further, the amount of noise increases in proportion to the reproduction frequency band. If the reproduction frequency band is widened in order to improve resolution, therefore, image quality declines, even in the case of a monochrome video signal. For these reasons, modifying the reproduction frequency band has not been considered viable heretofore.